1. Field of the Invention
The present invention relates to, for example, a ceramic electronic component including a multilayer ceramic capacitor, and a mounting structure for the ceramic electronic component.
2. Description of the Related Art
A multilayer ceramic capacitor, which is a ceramic chip-type electronic component is typically used. In a case in which the multilayer ceramic capacitor is directly mounted on a mounting substrate by soldering, when the temperature changes, the mounting substrate and an electronic component body are expanded or contracted depending on their thermal expansion coefficients. However, the difference between the thermal expansion coefficients of both may cause, for example, a stress that may result in damage of the electronic component body or breakage of a joint portion.
Moreover, in a case in which the mounting substrate easily bends, such as a thin glass epoxy board, a stress may also be generated when the mounting substrate bends.
Furthermore, a stress may be generated when a force is applied to the mounting substrate and the board is deformed in a bending manner.
Such a stress applied to the multilayer ceramic capacitor may cause a crack to be generated in the multilayer ceramic capacitor. To address the problems, it has been suggested to attach a metal terminal made of a metal plate to an outer electrode of the multilayer ceramic capacitor, to keep the electronic component body in a state lifted and spaced away from the mounting substrate, and to mount the metal terminal on the mounting substrate by soldering (see Japanese Unexamined Patent Application Publication No. 2001-189232).
With such a method, the heat during the soldering is transmitted to the electronic component body via the metal terminal. A heat shock is less likely to be applied to the electronic component body. Moreover, even if a stress is generated due to a change in temperature or if the mounting substrate is deformed, the electronic component body can advantageously absorb the stress or deformation by elastic deformation of the metal terminal.
Also, welding is known as a way of mounting a connection terminal on a mount point (for example, laser welding for a method that can reduce the welding time) (see Japanese Unexamined Patent Application Publication No. 11-191472).
However, in a case in which the electronic component with the metal terminal as described in Japanese Unexamined Patent Application Publication No. 2001-189232 is mounted on the mounting substrate by soldering in a device (on-vehicle device) that is used in a high-temperature environment, the component may detach or fall from the mounting substrate due to molten solder joining the metal terminal and the mounting substrate, or the solder may be fragile because the solder is exposed to high temperatures for a long period even if the temperature is lower than the solder melting temperature. The equivalent series resistance (ESR) may be increased and the adhesion intensity may be decreased by the formation of a solder crack. A typical method of avoiding the problems may be a method of using solder having a high-temperature melting point. However, there is actually no solder that satisfies the cost, mountability, and performance requirements capable of addressing the above-described problems.
Also, a typical welding mount technology as described in Japanese Unexamined Patent Application Publication No. 11-191472 needs to press the metal to be connected against a portion at which the metal is to be welded, and connect the metal by applying current to the metal in a secure surface-contact state and thus melting the metal. If the technology is applied to the electronic component with the metal terminal as described in Japanese Unexamined Patent Application Publication No. 2001-189232, it is required to perform the connection by bringing a connection terminal member of the metal terminal to be mounted securely into surface contact with the mounting surface of the mounting substrate. The connection is time consuming.
In the case in which the laser welding as described in Japanese Unexamined Patent Application Publication No. 11-191472 is applied to the electronic component with the metal terminal as described in Japanese Unexamined Patent Application Publication No. 2001-189232, it is a precondition that the connection terminal member of the metal terminal member to be mounted is securely in surface contact with the mounting surface of the mounting substrate. At this time, it is difficult to obtain the state in which the portion subject to welding is securely in contact due to the problems of warpage of the mounting substrate and coplanarity of the electronic component (flatness of component (in the case of the metal terminals, shift between mounting surfaces of left and right metal terminals). The difficulty in the contact may result in welding defects.
Also, the metal terminal having a metallic luster reflects laser energy, so the metal terminal member cannot be efficiently welded.
Another method of laser welding the electronic component while pressing the electronic component has been conceived. However, the speed of laser welding obtained because of the non-contact state cannot be achieved.